Water is one of the factors that causes short circuit of electronic elements. As water can permeate easily, even the electronic element that is protected by a casing could be damaged by seeping of water. The switch to conduct electric current could result in fire breakout due to exposure to water. The consequence is serious.
To remedy the aforesaid problem, many waterproof switches have been developed. R.O.C. patent No. 496567 discloses a waterproof switch which mainly has a waterproof washer in a main body to prevent water from entering in the circuit located inside.
Other references of waterproof switch design can be found in R.O.C patent Nos. 551595 and 495089 and the like. They all use a washer in the switch body to achieve waterproof effect. However, they all aim to provide waterproof function for the interior of the body. The connection juncture between pins and electric wires also is an important spot. Whatever waterproof effect of the waterproof washer, short circuit occurred to the connection juncture of the waterproof switch pins and electric wires also causes damage of the switch and results in unforeseeable loss. There is a conventional method which adopts a heat-shrinking tube to encase the exposed core of the pin and electric wire to achieve an insulation effect. But it cannot fully seal the pin and electric wire. This is especially true on the connection juncture of the pin and body where insulation is unattainable by the heat-shrinking tube.
Moreover, electric connection effect of the core of electric wire and the pin also is a troubling issue. As the core and the pin are usually bonded by soldering, their connection is not sturdy. In the event that the core is pulled or twisted, the juncture on the pin could fracture or loosen and result in a poor connection.
Refer to FIG. 1 PRIOR ART for a conventional technique to overcome the aforesaid problems. It provides a waterproof structure for switch pins. It has a switch body 10 with a cavity 11 to hold a pin 12. The connection juncture of the pin 12 and an electric wire is located in the cavity 11. After the pin 12 and the electric wire 20 is connected, an insulation material 30 is filled in the cavity 11 to embed the electric wire 20 and pin 12 together, thereby to achieve waterproof effect.
FIG. 2 PRIOR ART shows another conventional technique. It has a shell 40 fastened to an outer end of a switch body 10 where a pin 12 is located. The connection juncture of the pin 12 and an electric wire 20 is covered by the shell 40. The electric wire 20 is extended outside by threading through an opening 41 formed on the shell 40 and switch body 10. Then an insulation material is filled in the shell 40 by injecting in a paste fashion through the opening 41 to seal the connection juncture of the pin 12 and the electric wire 20.
While the two conventional techniques mentioned above can form a sturdy anchoring for the electric wire 20 and fully cover the connection juncture of the electric wire 20 and the pin 12 to achieve waterproof effect, the paste could spill outside. Moreover, injecting the paste manually is slow and often results in unstable quality. It is not economic effective.